1. Technical Field
The present invention relates to a seat belt retractor for use in a vehicle. Particularly, the present invention relates to a seat belt retractor having an inertia actuated locking pawl and to a method of assembling the retractor.
2. Description of the Prior Art
A seat belt retractor for restraining a vehicle occupant in emergency situations typically includes a spool with seat belt webbing wound on the spool. The spool is supported for rotation in belt withdrawal and belt retraction directions. A locking mechanism comprises a pair of ratchet wheels fixed to the spool, a pivotally mounted pawl, and an inertia member, such as a pendulum, for pivoting the pawl into engagement with the ratchet wheels. The locking pawl is biased by a spring or by gravity to a position disengaged from the ratchet wheels. Movement of the inertia member from an unactuated position, in response to deceleration or other rapid change in the movement of the vehicle, causes the locking pawl to pivot into engagement with the ratchet wheels and lock the spool against rotation in the belt withdrawal direction.
The inertia member is suspended in a generally vertical direction in its unactuated position so the safety belt may be freely withdrawn by the vehicle occupant without locking the spool. However, it is desirable to mount the retractor in various positions and in different orientations within different vehicles, or even within the same vehicle. Thus, it is necessary to design different supports for the inertia member to accommodate different retractor mounting positions or orientations and still suspend the inertia member vertically.
U.S. Pat. No. 3,938,754 discloses a seat belt retractor including a pendulum supported by a flywheel. The pendulum engages a post attached to a locking pawl and upon movement of the pendulum the pawl is pivoted to lock the retractor. The flywheel is pivotally supported by the retractor so the pendulum is suspended vertically regardless of the orientation of the retractor.
U.S. Pat. No. 3,938,755 discloses a pendulum housing supported for pivotal movement. A pendulum is supported by the pendulum housing and engages a post attached to a locking pawl of the retractor to pivot the pawl. The pendulum is in a vertical orientation regardless of the orientation of the retractor.
U.S. Pat. No. 4,556,177 discloses a pendulum pivotally supported by a spherical housing which, in turn, is pivotally supported by the seat belt retractor. The retractor may be mounted in a vehicle in a number of different orientations without having to change parts so the pendulum is suspended vertically. The pendulum moves an intermediate actuating rod which moves a pivotable lever which, in turn, pivots the pawl.
U.S. Pat. No. 3,897,913 discloses a pendulum supported for pivotal movement by a bearing having a semi-spherical portion received in a semi-spherical recess. A planar surface of the bearing engages a plunger which engages a spring biased locking control member.